Equilibria involving ions: acids and bases. AH Unit 2(b)(iii). Key question. What is are acids and bases?. Arrhenius definition. An acid is a substance that when added to water increases the concentration of H + (aq) ions . HA + (aq) H + (aq) + A - (aq)
AH Unit 2(b)(iii)
HA + (aq) H+(aq) + A-(aq)
BOH + (aq) B+(aq) + OH-(aq)
HA H++ A-
HA + H2O H3O++ A-
B + H+ BH+
B + H3O+ BH+ + H2O
This is a measure of the strength of an acid
- the larger the value of Ka, the stronger the acid.
This is a measure of the strength of a base
- the larger the value of Ka, the weaker the base.
Supplies H3O+(aq) ions if any removed in reacting with an added base.
CH3COONa(s) → Na+(aq) + CH3OO-(aq)
The conjugate base removes any added H+(aq)
Because the by diluting a buffer the concentration of acid and salt will decrease in proportion, dilution will not affect the pH of a buffer solution.